A 71-year-old man with dilated cardiomyopathy and complete atrioventricular block underwent cardiac resynchronization therapy (CRT) due to chronic heart failure that was not improved by conventional medical treatment. But we found the coronary vein ostium was completely obstructed by coronary venography. The contrast medium flowed out from the right atrium via a collateral pathway. Thus a left ventricular lead was placed via a collateral pathway and was successfully implanted without complications. The postoperative threshold was 2.7 V at 0.4 ms. The subjective symptom improved after CRT. The safety of this procedure was not clear.